As communications technology improves and demand for communication services grows, providers often seek to adjust those systems to incorporate the improved technology and expand those systems to accommodate the growing demand. Systems that are slow to adjust or expand can be undesirable and are often rendered obsolete. Systems that expand by providing unnecessary redundancy are inefficient and costly. Advances in telecommunication technologies create opportunities for integrating communication capabilities as well as challenges for transitioning between technological generations. Presently, some telecommunication consumers are subscribed for full access to services of internet protocol multimedia systems (IMS), while others are subscribed to legacy, non-IMS systems. It is desirable to allow non-IMS consumers to selectively access some IMS-based services, such IP-based messaging, while prohibiting similar access to IP-based voice calls to facilitate consumer acceptance and satisfaction with the IMS system while retaining incentives for full subscriptions.